Many questions related to the clinical treatment of obesity remain unanswered despite available data. In part, this appears due to inadequate data accumulation. When multiple studies address a question, results are not always combined in quantitative, objective, and comprehensive ways to yield clear answers. We aim to demonstrate the power of meta -analysis for obesity research and to demonstrate athe conduct of thorough, rigorous, and sound meta-analyses. We will address four specific questions regarding clinical issues in obesity. These questions are selected on the basis of substantive importance and ability to demonstrate different meta-analytic procedures. The first question asks what is the proportion of obese adults ina the community that intentionally lose a clinically meaningful amount of weight and maintain that weight loss for some minimum duration of time. This question is important because it has been suggested that success rates for weight loss are higher in the general community than ina the treatment studies that have been reported. The second research goal is to develop equations to predict an individual's weight at time given that they are undergoing caloric restriction and that one knows their age, sex, and body mass index at time O. Such equations would be quite useful for predicting weight loss as well as for prescribing levels of caloric reduction that would result in safe rates of weight loss. The third goal is to develop "growth curves" to estimate the natural course of weight change for obese adults. Such curves can present the "baseline" against which to judge the success of weight loss treatments. That is, these growth curves can be used to answer the question "What would we have expected this person's weight to be if he/she had never undergone treatment. The fourth question asks what are the relative effects on cardiovascular disease (CVD) risk factors (e.g., blood pressure, glucose tolerance, serum lipids) of changes in weight, total fat mass, and visceral fat mass among obese adults undergoing voluntary weight loss? This is important because if loss of different body components more strongly relates to reduction in CVD risks than loss of other body components, it provides a richer set of criteria by which interventions can be judged.